Flow switch



Sept. 13, 1960 L. J. KMlEClK ET AL 2,952,753

FLOW SWITCH Filed June 27, 1958 2 Sheets-Sheet 1 INVENTORS.

Sept. 13, 1960 L. J. KMlEClK ETAL 2,952,753

FLOW SWITCH Filed June 27, 1958 2 Sheets-Sheet 2 INVENTORS.

United States Patent FLOW SWITCH Leopold J. Kmiecik, Lincolnwood, and Elwood H. Stonich, Chicago, Il]., assignors to McDonnell & Miller, Inc., Chicago, 111., a corporation of Delaware Filed June 27, 1958, 'Ser. No. 744,969

'10 Claims. (Cl. ZOO-81.9)

Our invention relates to electrical switches and particularly to an improved switch assembly which is operably responsive to the start or stop of liquid flow.

In general, the switch of our invention provides an economical and dependable control device useful in theactivation of pumps, burners, alarm meters, or similar devices where the flow of liquid in a pipe is of critical significance. Some of the more common fields of application are found in the starting or stopping of a burner in commercial water heaters, the control of a compressor in an air circulation system, the energization of a standby pump upon failure of a primary pump, or as a flow indicator in liquid process systems and the like.

In brief, our improved switch is adapted to be fitted in a T-connection associated with a horizontal pipeline where a horizontal run of the liquid is encountered. Suitable paddle means are embodied therein for moving an actuating arm which pivots about an axis located exteriorly of the pipeline and is sealed therefrom by a flexible bellows seal. The actuating arm carries a suitable finger portion at its upper end for engaging the plunger of an electrical control switch and such may be arranged to maintain the switch contacts open or closed in response to the flow of fluid through the pipeline with which it is associated. Other features include a multipart paddle system which readily adapts the same to various diameter pipelines and a unique adjusting system for regulating the throw of the paddle required to operate the switch contacts. Additional means are provided for adjusting the sensitivity of the paddle means to the flow or velocity of fluids in the pipeline.

The main object of this invention is to provide a new and improved switch assembly which is operable in response to flow of liquids or the interruption of such flow, as selected.

Another object of this invention is to provide a new and improved flow switch, as aforesaid, which embodies improved means for adjusting the sensitivity of a flow responsive switch actuating mechanism.

A still additional object of this invention is to provide a new and improved flow switch including a unique multipart paddle means which is adapted to depend into a fiuidcarrying conduit and is adjustable to multiple conduit diameters.

A still further object of this invention is to provide a new and improved flow switch which is readily conditioned for either a normally closed or a normally open circuit operation.

The above and further objects, features, and advantages of our invention will appear to those skilled in the art from the following detailed description and specification of a preferred embodiment thereof, as illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a schematic view in side elevation, with parts broken away, illustrating a typical installation arrangement for a switch of our invention;

Figure 2 is an enlarged sectional view of our switch,

Patented Sept. 13, 1960 looking from line 22 of Figure 1, and showing the elements therein arranged for normally closed circuit operation;

Figure 3 is a cross-sectional view taken substantially at line 3-3 of Figure 2 and looking in the direction of the arrows thereon;

Figure 4 is another plan view, similar to Figure 2, showing the electrical switch unit removed;

Figure 5 is an enlarged cross-sectional view taken substantially at line 55 of Figure 2, to illustrate details of our improved switch adjusting means;

Figure 6 is a sectional View, similar to Figure 3, in which elements of our improved assembly have been rearranged to provide for normally open circuit operation; and

Figure 7 is an enlarged partial end elevation of the switch assembly seen in Figure 6.

Turning now to the features of our improved flow switch and particularly referring to Figure 1, it will be understood that the switch assembly, indicated generally at 10 therein, is adapted to be associated with a horizontal fluid carrying conduit or pipeline 11 by threadingly connecting a mounting base member 12 thereof with a T-fitting 13 in the pipeline. The switch assembly 10 also includes a paddle means 15 which depends into the interior of the pipeline and traverses the fitting 13 so as to respond to the flow of liquid through the pipeline in such a manner that either the start or stopping of fluid flow may pivot the paddle means to operate switch contacts, as will later appear, for controlling an associated electrical circuit, for whatever purposes desired. If a T-fitting 13 is not available, the flow switch may be connected to the pipeline 11 by a fitting selected to be of a minimum length and welded directly to the pipeline about an opening suitable for the passage and operation of the paddle means 15.

With respect to the paddle means 15, it is essential that the same be positioned at right angles to the flow of the fluid and that it extend substantially across the interior of the pipeline to be properly responsive to the flow of liquids therethrough.

With reference now to Figures 2 and 3 0f the drawings, the base member 12 may conveniently be cast of brass to include a generally tubular body 16 having wrench engaging faces forming a polygonal exterior and a reduced diameter adjacent its lower end to define a connecting cylindrical neck portion 17 having external pipe threads 18 for connection with the fitting 13, as previously related. The base member 12 also includes a circular flange 19 at its upper end which is attachable to a lower rectangular base wall 20 of a metal switch housing, indicated generally by numeral 21.

The switch housing, in addition to base wall 20, includes a pair of upwardly extending end Walls 22, 22 and a platform wall 23 which extends between the end walls 22, 22 in spaced parallelism to the base wall 20. Upwardly turned attachment cars 24, 24 are provided on opposite side edges of the base wall to receive holding screws 25 which serve to lock a removable cover 26 in position; the latter extending between and across the two end walls, as seen best in Figure 3.

Mounted within the switch housing and particularly supported on the platform wall 23 (see Figure 2) is a switch assembly, indicated generally by numeral 30, which is actuated in response to pivotal movement of the paddle means 15. The switch assembly is positioned over an enlarged central opening 31 formed in the platform wall 23, and is attached to the latter by means of a pair of attachment screws 33, 34 which pass through elongated openings 35 and 36, respectively, formed in the switch supporting base plate 38. The base plate 38 comprises a substantially rectangular metal plate having the two 3 elongated openings 35 and 36, as aforesaid, which have their longitudinal axes directed substantially at right angles to one another. Plate 38 also is equipped with a depending pivot pin 40 adjacent one corner and an eccentric adjusting means41 near such pivot pin. A suitable rectangular opening 42 is also formed near one edge of the plate for passageofan upwardly extending operating finger 43associated with the'paddle assembly 15'. Opening 42 is substantially encased on the upper side of the base plate 38 by a housing which includes a pair ofparallel spaced endwalls 45,45, a side wall to, and a top wall 47 formed integrally withthe base plate and folded toprotect the plunger button 49 of a plunger actuated switch unit 50.

The switch unit 50 is mounted on the upper face of the base plate 38 and held in place by a pair of holding bolts 51, 51 which pass through the switch unit and thread into openings formed in the base plate. The switch unit is also insulated from the base plate by an intervening insulating shield 52 and presents terminal connectors 54 and 55 (see Figure 2) for connection with electrical leads in a conventional manner. A shield disc 56 is preferably provided beneath the head of one of the mounting bolts 51 to avoid short-circuiting contact with the conductor lead fastened to terminal 54. A switch (not shown) suitable forpurposes of unit 50 may be made according to the concepts and teachings found in United States Patent No. 2,232,996, issuedFebruary 25, 1941.

With reference now to Figure 3 in particular, it will be understood that the plunger operating finger 43 moves arcuately toward and away from the switch plunger 49 in accordance with movements of the paddle assembly 15, the details of which will now be set forth. As previously related, the base wall 20 of the switchhousing 21 is attached to the circular flange portion 19 at the upper end of the cast base member. The flange portion 19 substantially closes over the upper end of the tubular body portion 16 for the base member except for a central opening 60 through which the paddle assembly 15 extends. The upper face of the flange portion is further distinguished by a central raised circular pad 61, which projectsinto a correspondingly shaped opening 62 formed in the housing base wall 20. Plural screw elements 63 are used to interconnect the base wall of the housing to the flange portion 19. The base member 12 also includes trunnion posts 65, 65 which are cast integrally with the flange portion 19 and project upwardly from the pad 61 into the lower interior of the switch housing to support the paddle assembly, as will appear hereinafter.

The paddle means 15 includes an arm member 70 which depends beyond the lower end 71 of the base member 12 and is formed with a curved lower end portion 72. Aplurality of paddle leaf members, herein shown as three in number. and indicated at 75, 76, and 77, are attached to the arm 70 by a single bolt means 78 which threads into a suitable opening formed in the arm 70. A pin 79 is also upset from-arm 7th to pass through the leaf members 7577 to locate the same and prevent their turning about the bolt 78.

The several leaf members, as shown in Figure 3, are stacked one on top of the other and are of different lengths to form a cascade structure. It will be noted also that the leaf elements are placed on the upstream side of the arm 70 so as to bend with the flow of the fluid toward the curvilinear portion 72 of the paddle arm for better support. The provision of the plural leaf elements 75-77 readily adapts the paddle assembly to various diameter pipelines, and provides an effective system for regulating pivotal reaction of the paddle assembly to the force of fluid flow by selectively varying the eflective paddle area. Thus, with the three leaf elements combined (see Figure 3), the paddle assembly is adapted to larger diameter pipelines, such as 3-inch pipeline and presents a maximum contact area to the'flowing fluid. Byremovingleaf 75 from the assembly, a shorter paddle assembly of intermediate area is defined, suitable for intermediate pipe diameters, as in a 2-inch pipeline, or such may be used in larger pipes to reduce the paddle area and the force tending to pivot the same. The third and remaining leaf element 77, used alone, is suitable for smaller pipelines and provides a minimum paddle area.

To support the paddle arm 70, its upper end is held by pin means 80 in a slot cut through the lower end of a cylindrical retainer member 81 which extends upwardly through the opening 60 in the platform portion of base member 12. Thus, the retainer 81 extends into the interior of the switch housing 21.

In order to provide aseal between the interior of the pipeline 11 and the switch housing, theupper end of the retainer 31 is encased by a flexible bellows 82 which is brazed or otherwise rigidly aifixed and sealed to the platform portion 61. The upper end of the bellows is sealed between the upper end of the retainer 81 and an overhanging pivot beam 85, the switch actuating finger member 13 and a retainer bracket 86 which overlies the switch actuating finger 43. In so connecting the upper end of the bellows to the several elements described, a single holding screw 87 is employed over a seal washer 88 (see Figure 4) which passes through a rectangular platform portion 89 of the retainer bracket 86, a lower arm portion 9llof the actuating finger member 43 and through the upper end of the bellows 82 for threaded connection with the upper end of the arm retainer 81. in this manner, aneifective seal is provided between the interior of the fluid carrying pipeline and the interior of the switch housing, while permitting movement of the paddle arm assembly with the flow of fluid Within the pipeline.

To achieve the desired movements of the paddle assembly, the same is pivotally supported intermediate its ends so that arcuate movement of the paddle leaf elements and paddle arm 70 in one direction, according to the flow of fluid in the pipeline, produces opposite arcuate movement of the plunger contacting finger 43. To this end, the bellows pivot beam is formed with a central platform portion which is flanked at its opposite ends by depending ear portions 96, each provided with a knife-edged projection 97 which extends into a trunnion receptive opening 98 formed near the lower ends of the depending ear portions 96. In particular, trunnion pins 100 are held in the laterally spaced trunnion posts 65 which extend upwardly and from the pad 61 of the base support member 12; such trunnions, as viewed in Figure 3, being formed with lengthwise extending wedge-shaped slots 102 which receive the knife-edged projections 97.

The bearing trunnions 100 are held in place in the trunnion posts 65 by means of set screwmembers 106 with the knife-edge support, so formed, being disposed on the underside of the trunnion members. The bellows $2 is also placed under slight axial compression, thereby serving to resiliently hold the knife-edge projections securely on their trunnion supports. In this manner, the paddle assembly 15 is supported for pivotal movement about a horizontal axis, as defined by the trunnion members 100, and located externally of the pipeline.

In order to control the sensitivity of the paddle assembly to the flow of fluid through the pipeline 11, a simple adjustment means is employed including a coil spring 106 held between an upwardly extending ear portion 187 associated with the finger retaining bracket 86 and a depending ear portion .108 struck downwardly from the platform wall 23 of the housing. An adjusting screw means 109 threads through a sheet metal lock nut .110 mounted on the ear portion 1% to adjust compression of the spring means 1% through a pilot collar 111 which bears against one end of the spring and receives the inner end of the adjusting screw. The other end of the spring is piloted over a nipple member 112 which projects from the upwardly turned ear portion 107 of the finger retaining bracket. It will be appreciated, therefore, that adjusting screw means 110 produces a variation in the compression of spring 106 and serves, in turn, to thereby vary or adjust the force required to pivot the paddle assembly 115 about its pivotal axis trunnions 100; spring 106 opposing the movement of the paddle assembly with the flow of the fluid in the pipeline.

From the foregoing description, it will be recognized that the flow switch assembly of Figures 2 and 3 is designed for normally closed switch operation in response to the flow of fluid through the pipeline, such flow being according to the direction of arrow A or from right to left, as viewed in Figure 3, for example. In this operating condition, the switch 50 is positioned so that its plunger 49 is depressed by the movement of the finger element 43 theretoward, and serves thereby to open contacts of the switch means 50. However, due to the fact that it is not always possible to achieve uniform contact and plunger throw in a production switch unit, such as switch 50, it is essential that some means he provided for adjusting the relative position between the extended switch plunger 49 and the switch operating finger member 43. This is accomplished in a very simple and direct manner by the previously referred to eccentric 41 associated with the switch base plate 38.

The relationship and operation of the eccentric 41 may best be understood by examining Figures 4 and 5 of the drawings, but to fully recognize its operation, a review of the means employed to interconnect the base plate 38 of the switch assembly 30 and the platform wall 23 of the switch housing will be made at this junction, particular reference being made to Figures 2 and 4. It will be recalled that the base plate of the switch assembly is equipped at its diagonally opposite corners with slotted openings 35 and 36 which receive the mounting screws 33 and 34 and have their longitudinal axes generally at right angles to one another. Adjacent the elongated opening 35 is the eccentric means 41, as will be described in more detail presently, and next adjacent to the eccentric means is the depending pivot center or projection 40. This relationship is particularly shown in Figure 5 of the drawings.

As seen best in Figure 4, the intermediate platform wall 23 of the switch housing is equipped with the central opening 31 through which the upwardly extending resilient plunger actuating finger member 43 extends. Adjacent the opposite lateral ends of wall 23 and on the central axis thereof, are a pair of identical elongated oval openings 124 and 125 adapted to receive the eccentric 41. At substantially diagonally opposite corners of the central opening 31 are additional openings 126 and 127 which are intended to receive the depending pivot member 40 when associated with the switch assembly base plate 38. Adjacent the opposite diagonal corners of the central opening 31 are additional threaded openings 128 and 129 which receive the mounting bolts 33 and 34, respectively, for locking the switch assembly and particularly its base plate 38 in a desired position on top of the platform wall 23.

Referring now to Figure 5, it will be seen that the eccentric member 41 comprises essentially a screw element having an upper head portion 130 equipped with a slot 131 receptive of a screwdriver blade or a like instrument for effecting its rotation. Beneath the head portion 130 and designed to be received concentrically within a suitable opening formed through the switch. base plate 38, is a cylindrical shank portion 132 which is coaxially aligned with the head portion 130. An eccentrically aligned axle crank portion 134 depends offcenter from the shank portion 132 thereof and is equipped with an annular washer element 135 at its outer end. The washer 135 enters the slotted openings 124 or 125, as selected, and is disposed beneath the base plate 38 of the switch assembly.

In the arrangement of Figures 2 and 3, for example, the eccentric 41 enters the slotted eccentric opening 124 '3 (see Figure 6).

of the wall 23 and the pivot pin 40 enters the pivot center opening 126. With this arrangement, rotation of the eccentric in the opening 124 causes pivotal activity of the switch assembly 30 about opening 126 as a pivot center between the dotted-line positions LL and LR in Figure 4.

Such eccentric adjustment of the switch assembly serves to regulate the spacing between the free switch plunger 49 and the actuating finger 43 to accordingly adjust the operational characteristics of the switch and particularly to insure that the contacts of switch 50, as seen in Figures 2 and 3, are closed when fluid is flowing through the pipeline 11. This eccentric adjustment, when employed in conjunction with the adjustment means 105, serves to regulate the switch assembly for both velocity of fluid flow through the pipe and the sensitivity of the switch plunger in response to movement of the actuating finger 43. Thus, for example, by moving the switch plunger toward the finger 43, less movement of the paddle assembly is required to close the switch contacts and vice versa.

In Figures 6 and 7 we have shown a modified version of the switch assembly hereinabove described in which the switch unit 50 is rearranged to provide for a normally open contact operation in response to flow of fluid through the pipeline. To accomplish this reversed operation, it is necessary to position the switch operating finger member 43 by loosening the screw means 87 and swinging such approximately so that the same is disposed on the opposite side of the central opening 31 in barrier wall 23 from its position illustrated in Figure With the operating finger 43 so rearranged, it is next essential to reverse the positioning of the switch unit 50. This is done by removing the holding screws 33 and 34 and rotating the entire switch assembly, including the base plate 38 thereof, 180 to agree with the repositioning of the plunger actuating finger. In this reverse condition, the pivot pin 40 will enter and cooperate with the alternate pivot center opening 127 in wall 23, While the eccentric 41 will reside in the adjacent eccentric opening 125. So conditioned, rotation of the eccentric 41 will serve to move the entire switch assembly between the dotted-line limit positions shown at RR and RL of Figure 4, respectively.

It will be understood that the alternate assembly of Figure 6 is identical with that shown in Figures 2 and 3, with the exception of the reversal of the switch assembly 50' therein and the switch operating leaf member 43', as above described. It will be noted that the flow of the liquid in the pipeline 11 remains as before, or from right to left, as viewed in Figure 6. Therefore, pivoting of the paddle assembly 15 in response to flow of liquid in the pipeline will serve to move the switch operating leaf member 43' away from the plunger 49, maintaining the switch contacts open so long as fluid continues to flow through the pipeline in amounts and at a velocity sufiicient to meet the adjusted conditions of the switch.

From the above description, those familiar with the art will readily recognize the novel advancement and versatility which the improved assembly of our invention provides and particularly will appreciate the merit involved in the reversibility of the switch unit 50 to provide for normally open or normally closed circuit operation. Further, the provision of an eccentric adjustment for the switch assembly 30 readily adapts the same to utilization of a production model switch unit in which the throw of the switch plunger may vary, since by providing means for so adjusting the spacing between the switch plunger and the operating finger of the paddle assembly, uniform opening and closing operation of the switch contacts may be achieved in a reasonable, efficient and simple manner.

It is also to be recognized that while we have hereinabove set forth the features and concepts of our invention as they pertain to a particular embodiment, illustrated in the drawings and above described, such as not necessarily to be limited to the details described, except as may appear in the following appended claims.

We claim:

1. In a flow switch adapted to operatively respond to fluid'flowing in a pipeline, a housing including a base portion adapted for connection in the pipeline, the interior of said base portion communicating with the interior of the pipeline, a paddle means mounted in said base portion and having one end depending into the pipeline and the other end projecting outwardly of said base portion, flexible seal means having connection with and encasing said paddles other end and preventing the escape of fluids from said base portion to the interior of said housing, means within said housing pivotally supporting said paddle means adjacent its said other end and exteriorly of said seal means, an electrical switch assembly including a plunger operated switch unit mounted in said housing and exteriorly of said seal means, finger means extending outwardly from said seal means into said housing and having connection with the said paddle for movement with the latter and operativelyengageable with the plunger of said switch unit, means for regulating the pivotal sensitivity of said paddle means to the flow of fluids in the pipeline, and eccentric means within said housing for adjustably pivoting saidswitch unit about an axis transverse to the pivotal axis of said paddle, operation of said eccentric means serving to position the switch unit and adjust the pivotal throw of said paddle means required to operate said plunger.

2. The combination as set forth in claim lin which said switch unit and operating finger means are arranged to depress said plunger in response to pivotal movement of said paddle with the flow of fluid in the pipeline.

3. The combination as set forth in claim 1 in which switch unit and paddle means are arranged to move said operating finger away from said plunger in response to pivotal movement of said paddle with the flow of fluid'in the pipeline.

4. The combination as set forth in claim '1 in which said switch unit may be selectively positioned for closed and open contact operation in response to pivotal movement of said paddle with the flow of fluids in the pipe line and in which said eccentric means is operable to adjust the positioning of the switch unit for both open and closed contact operation.

5. In a switch assembly adapted to operatively respond to the flow of fluids in a pipeline and like fluid carrying conduits, the combination comprising, paddle means adapted to have one end thereof engaged by the flowing fluid, pivot means supporting said paddle means intermediate its ends for movement about a substantially horizontal axis, a finger means attached to the upper end of said paddle means and extending upwardly therefrom, a switch housing'surrounding saidpivot means and the upper end of said paddle means and including a platform wall overlying said pivot means, said platform wall having an opening for the passage of said finger means therethrough, a switch means mounted on said wall and having pivotal connection therewith for movement about a substantially vertical axis disposed laterally of the longitudinal axis of said paddle means, eccentric means for adjustably pivoting said switch means between limits, an operatormeans on said switch means for operating circuit controlling contacts thereof, the adjustment of said eccentric means serving to regulate the distance between the extending finger means and the said switch operator means, thereby to adjust the pivotal throw of saidpaddle meansnecessary to operate said switch means, and means detachably mounting said finger means on said paddle means whereby the same may be disposed on opposite sides of the longitudinal axisof said paddle means and offset therefrom to provide movement of said finger means selectively toward and away from said operator means in response to pivotal movement of said paddle means in one direction.

6. A flow switch comprising housing means, paddle means pivotally mounted intermediate its ends for movement about a fixed axis, said paddle means having one end thereof extending outwardly of anopening of said housing and having its other end lying within said housing, seal means surrounding saidother end of said paddle means for closing said opening to prevent fluid from entering the interior of said housing through said open Sing, switch means including actuating means therefor,

means for mounting said switch means within said housing to dispose said actuating means in position to be engaged by said other end of said paddle means, and said mounting means including pivot means and eccentric means for 'pivotally adjusting the position of said switch means about said pivot means to dispose said actuating means in predetermined position relative to said other end of said paddle means.

7. The flow switch of claim 6 characterized .by the provision of spring means having connection with said paddle means to yieldinglyoppose movement of the latter aboutits axis, and means for adjusting said spring means.

8. A flow switch comprising a housing, a base member for said housing having an opening therein, baflie means having one end extending outwardly through said opening and the other end extending into said housing, means between said base member and said other end of said baffle means to close said opening and prevent fluid from passing therethrough into said housing, means within said housing between said other end of said baffle vmeans and said base member affording substantially knife edge pivotal mounting of said baffle means about a substantially horizontal axis, a platform mounted within said housing in spaced relation tosaid base memher and adjacent said other end of said baffle means, switch assembly means including a snap action switch carried by said platform, a plunger for .said .switch means for actuating the same, switch trippingmeanscarried at said other end of said baffle means andextending through an opening on said platform for engaging said plunger upon pivotal movement of said baflle means about its axis, adjusting means between said switch assembly means and said platform including pivot means therebetween, and eccentric means for moving said switch assembly relative to said platform about said pivot means to dispose said plunger in a predetermined position relative to said other end of said paddle means.

9. A flow switch comprising a housing, a base member for said housing having an opening therein, baffle means having one end extending outwardly through said opening and the other end extending into said housing, means between said base member and said-other end of said bafile means to close said opening and prevent fluid from passing therethrough into said housing, means within said housing between said other end of said baffle means and said base member affording substantially knife edge pivotal mounting of said bafile means about a substantially horizontal axis, a platform mounted within said housing in spaced relation tosaid base member adjacent said other end of said baffle means, switch assembly means including a snap action switch carried by said platform, a plunger for said switch means for actuating the same, switch tripping means carried at said other end of said baflie means and extending through an opening in said platform for engaging said plunger upon pivotal movement of said baflle means about its axis, adjusting means between said switch assembly means and said platform including pivot means therebetween, eccentric means for moving said switch assembly relative to said platform about said pivot means to dispose said plunger in predetermined position relative to said other end of said baffle means, spring means between said other end of said baffle means and said platform to yieldingly oppose movement of said baffle means about its axis, and means for adjusting said spring means.

10. A flow switch comprising a housing, a base member for said housing having an opening therein, baffie means having one end extending outwardly extending through said opening and the other end thereof extending into said housing, flexible bellows means between said other end of said baffle means and said base member closing the opening in said base member from the interior of said housing, mounting means between said base member and said other end of said baffle means including a pivot beam at said other end of said baflle means having depending ear portions formed with knife edges for cooperating with wedge shaped slots in trunnion pins carried by said base member to provide for pivotal movement of said baffle means about an axis parallel to the plane of said base member, a platform mounted Within said housing in spaced relation to said base memher and adjacent said other end of said baffle means, switch assembly means including a snap action switch carried by said platform, a plunger for said switch means for actuating the same, switch tripping means carried at said other end of said baffle means and extending through an opening in said platform means for engaging said plunger upon pivotal movement of said bafiie means, adjusting means between said switch assembly means and said platform including pivot means affording a pivotal axis extending normal to the pivotal axis of said baffle means, and eccentric means for moving said switch assembly relative to said platform about said pivot means to dispose said switch tripping means in predetermined position relative to said plunger.

References Cited in the file of this patent UNITED STATES PATENTS 1,994,970 Turner Mar. 19, 1935 2,038,111 Hopkins Apr. 21, 1936 2,119,783 Harrington June 7, 1938 2,176,338 Harrington Oct. 17, 1939 2,347,830 Kiburz May 2, 1944 2,583,814 Burklin Jan. 29, 1952 2,687,457 Smith Aug. 24, 1954 2,740,858 Euler Apr. 3, 1956 

